Trichosia (Trichosia) basiconstricta, Sutou & Menzel, 2025

Sutou, Mitsuaki & Menzel, Frank, 2025, The genera Mouffetina Frey and Trichosia Winnertz (Diptera, Sciaridae) in Japan with a key for the Japanese species and an updated world checklist, Contributions to Entomology 75 (1), pp. 167-182 : 167-182

Trichosia (Trichosia) basiconstricta sp. nov.

Fig. 6 A ‒ D

Type material.

Holotype. JAPAN • ♂; Honshu, Tokyo, Miyake Island, Hinoyama-touge ; 34°06'N, 139°33'E; 5–7 Apr. 2010; J. Aoki leg., flight interception trap; NSMT . Paratypes. JAPAN • 3 ♂♂, 2 ♀♀; same data as for holotype; 1 ♂, NSMT; 1 ♂, 1 ♀, SDEI; 1 ♂, 1 ♀, PCMS .

Description.

Male. Head: Eye bridge 3‒4 facets wide. Prefrons with setae and clypeus bare. Scape brown with about 5 setae anteriorly, pedicel brown with about 8 setae; flagellomeres dark brown except for yellowish brown base of 1 st flagellomere; 4 th flagellomere about 3.0‒3.5 times as long as wide, neck portion about 1 / 10 of its whole length (Fig. 6 A ), hairs yellowish brown and almost as long as width of flagellomere. Palpus brown, 3 - segmented with length ratio 1.5: 1.0: 1.6, 1 st segment with 5‒7 setae mainly on its outside and without distinct sensory area bearing minute sensilla, 2 nd segment with 6‒8 setae, 3 rd segment slender with 5‒8 setae (Fig. 6 B ). Thorax: Color predominantly dark brown; dorsocentral setae on mesonotum short, dorsolateral setae on mesonotum and setae on scutellum consist of longer and shorter ones; posterior pronotum with setae. Legs brown; tibiae and basitarsi of all legs with differentiated spine-like short setae in ground setosity; fore tibial spur about 1.1‒1.2 times as long as width of tibial apex. Wing with brownish anterior veins and light brownish posterior veins; wing membrane bare; R 5 with both dorsal and ventral macrotrichia, bM bare, r-m, M 1, M 2, stem of M, CuA 1, and CuA 2 with dorsal macrotrichia; length of R 1 = 0.7‒0.8 R, c = 0.7w, r-m = 1.0‒1.7 bM, stem of CuA very short, almost absent; R 1 ending at same level of or slightly beyond branching point of M 1 and M 2; wing length 2.9‒3.5 mm. Halter brown, knob with setae. Abdomen: Tergites and sternites brown with dark brownish setae, membrane between tergites and sternites yellowish brown. Gonocoxite wider than long with narrow base (Fig. 6 C ); gonostylus longer than wide, its inside moderately swollen on which many spines are present (Fig. 6 D ); upper half of tegmen rounded with two pocket-like structures (Fig. 6 C ); aedeagus nearly Y-shaped (Fig. 6 C ). Body size: 3.6‒4.4 mm.

Female. Similar to male, but hairs of 4 th flagellomere shorter than its width. Fore tibial spur about 1.3‒1.4 times as long as width of tibial apex. Wing length 3.0‒ 3.8 mm. Body size 4.5‒5.2 mm.

Remarks.

The structure of the gonostylus of this new species (Fig. 6 D ) resembles that of T. fumoranea (Fig. 5 D ) in having a swollen convexity on which many spines are present. However, this species can be easily distinguished from T. fumoranea in having shorter flagellomeres of antennae (Fig. 6 A ), completely bare wing membrane, constricted base of the gonocoxite (Fig. 6 C ), and rounded apex of the tegmen (Fig. 6 C ). The name of this new species is derived from the narrow, constricted base of the gonocoxite. This species is so far known only from Miyake Island, 175 km south of Tokyo metropolis.

Figures

Figure 5. Trichosia fumoranea sp. nov., male holotype. A. 4 th flagellomere; B. Right palpus; C. Genitalia, ventral view; D. Left gonostylus, ventral view; E. Inside of left foretibia; F. Right wing. Scale bars: 0.05 mm (A, B, D, E); 0.1 mm (C); 0.5 mm (F).

Figure 6. Trichosia basiconstricta sp. nov., male holotype. A. 4 th flagellomere; B. Left palpus; C. Genitalia, ventral view; D. Left gonostylus, ventral view. Scale bars: 0.05 mm (A, B, D); 0.1 mm (C).